76 G. W. SALISBURY 



Magnesium 



We have not been able to modify the metabolic behavior of either 

 spermatozoa in semen or of washed spermatozoa by normal varia- 

 tions of magnesium in suspension media. Our results suggest that 

 this cation serves primarily as an enzyme catalyst and that even cells 

 washed several times contain enough of it to function properly. 



EXPERIMENTAL MODIFICATION OF ANAEROBIC METABOLISM 



No one can be quite sure as to the gas exchange conditions exist- 

 ing at all levels of the mammalian male and female reproductive 

 tracts. Bishop has come as close to it as anyone when he found that 

 in the rabbit the p0 2 in the vasa deferentia was too low to support 

 (Bishop and Mathews, 1952), and in the female tubular genitalia 

 (Bishop, 1956) was sufficiently high to support aerobic metabolism. 

 Years ago Reclenz (Braus and Redenz, 1924; Redenz, 1925) theorized 

 that the absence of motility by the spermatozoa in the excurrent 

 ducts of the male was due to high pC0 2 . This view plus the lack 

 of carbohydrate substrate, the relatively high content of noncarbo- 

 hydrate reducing substances, the low p0 2 , the relatively high os- 

 motic pressure, the high level of potassium, and the low content of 

 calcium in the fluids of the caput and the corpus epididymis are all 

 part of our present working hypothesis. In addition, there is in bull 

 epididymal spermatozoa a diffusible substance (Lardy et al., 1945), 

 containing sulfur, found by Lardy et al. (1949), which they have 

 termed a metabolic regulator; in ejaculated semen there is an ap- 

 preciable amount of sulfite (Larson and Salisbury, 1953). 



The following figures and tables will show the present status of 

 our information on some of these points. 



Inhibition by Potassium 



Figure 8 shows the effect of potassium in Illini variable-tempera- 

 ture diluent (IVT K ) and of sodium (IVT Na ) as the primary cation 

 on 4-hour anaerobic glycolysis at 37°C of bull semen diluted 1 :4 with 

 citrate bicarbonate buffer, as measured by C0 2 evolution from bi- 

 carbonate (corrected for both C0 2 retention and acid retention in 

 the buffer) with N 2 as the gas phase (Lodge, 1960). Note again the 

 inhibitory effect of K+ on glycolysis under these anaerobic condi- 



